[media] V4L menu: remove duplicate USB dependency

Thanks to Guennadi Liakhovetski <g.liakhovetski@gmx.de> for pointing this
out to me.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>